JP4901194B2 - PHOTOELECTRIC CONVERSION DEVICE, MANUFACTURING METHOD THEREOF, AND PHOTOVOLTAIC GENERATION DEVICE - Google Patents

Description

  The present invention relates to a dye-sensitized photoelectric conversion device such as a solar cell or a light receiving element excellent in conversion efficiency, a manufacturing method thereof, and a photovoltaic device.

  Conventionally, a dye-sensitized solar cell, which is a type of photoelectric conversion device, does not require a vacuum device for its production, so it is considered to be a low-cost, low-environmental load-type solar cell, and is actively researched and developed. Has been done.

  This dye-sensitized solar cell is usually provided with a porous titanium oxide layer having a thickness of about 10 μm obtained by sintering fine particles of titanium oxide having an average particle size of about 20 nm on a conductive glass substrate at about 450 ° C. A photoactive electrode substrate in which a single molecule of a dye is adsorbed on the surface of the titanium oxide particles of the porous titanium oxide layer, and a counter electrode substrate in which a platinum or carbon counter electrode layer is formed on a conductive glass substrate The porous titanium oxide layer and the counter electrode layer are opposed to each other, a frame-shaped thermoplastic resin sheet is used as a spacer and sealing material, and both substrates are bonded by hot pressing, and iodine / iodide is interposed between these substrates. It is obtained by injecting an electrolyte solution containing a redox couple. In the solar cell thus obtained, the dye adsorbed on the porous titanium oxide layer as the porous oxide semiconductor layer absorbs the irradiated light energy, and the generated electrons move to the porous oxide semiconductor layer. Then, the electrolyte is transferred as ions from the counter electrode layer via an external load circuit and returned to the pigment, thereby being taken out as electric energy (see Non-Patent Document 1 below).

  However, since this dye-sensitized solar cell normally uses a single-layer porous oxide semiconductor layer, the amount of light absorption contributing to photoelectric conversion is small and the amount of light transmission is large. , Also referred to as conversion efficiency). Therefore, the configuration of Patent Document 1 in which a light-reflecting particle layer is provided on the back surface of the porous oxide semiconductor layer, the porous oxide semiconductor layer having a plurality of layers, each having a different fine particle size, There are configurations of Patent Documents 2 and 3 in which large light scattering particles are mixed in a physical semiconductor layer so as to function as a scattering layer.

  In Patent Document 1, an electrode is provided on the back surface of a glass substrate, a light absorbing particle layer in which semiconductor fine particles adsorbing a dye are deposited is formed on the lower surface of the electrode, and the lower surface of the electrode includes the light absorbing particle layer. In the dye-sensitized solar cell in which the electrolyte portion is provided and the counter electrode is provided on the lower surface of the electrolyte portion, a highly refractive material thin film is provided between the electrode and the light absorbing particle layer, and the light absorbing particles A dye-sensitized solar cell is described in which a light-reflecting particle layer in which high refractive material particles having a controlled particle size are deposited is provided on the lower surface of the layer. With this configuration, most of the energy of light that has been transmitted through the light-absorbing particle layer composed of semiconductor fine particles in the conventional structure can be absorbed and confined in this light-absorbing particle layer. The output current can be increased.

  Patent Document 2 discloses a transparent conductor layer, an n-type oxide semiconductor electrode formed by laminating fine particles, a dye adsorbed on the n-type oxide semiconductor electrode, and a charge transport layer in contact with the dye And a counter electrode in contact with the charge transport layer, the photoelectric conversion element having a larger average particle size of the fine particles on the charge transport layer side than the average particle size of the fine particles in the vicinity of the transparent conductor layer. Are listed. The average particle size of the fine particles near the transparent conductor layer is 5 to 50 nm, and the average particle size of the fine particles near the charge transport layer is 30 to 500 nm. Further, since it is necessary to make the light incident on the transparent conductor layer side without scattering, it is desirable that the particle diameter of the fine particles forming the n-type oxide semiconductor electrode be as small as possible. On the other hand, on the charge transport layer side, it is desirable that the pore diameter inside the n-type oxide semiconductor electrode, which is a porous body, is as large as possible so that ions as charge carriers can easily diffuse to the vicinity of the dye. With this configuration, more light can be absorbed by the complex dye, and the diffusion of charge carriers in the charge transport layer can be facilitated, resulting in an increase in energy conversion efficiency.

  The photoelectric conversion element of Patent Document 3 is a photoelectric conversion element having at least a layer of a semiconductor fine particle film on which a dye is adsorbed and a conductive support, and the layer of the semiconductor fine particle film is composed of a plurality of layers having different light scattering properties. A photoelectric conversion element in which a layer having the lowest light scattering property is disposed on the light incident side. Further, the layer having low light scattering property is composed of semiconductor fine particles having an average particle diameter of 5 to 50 nm, and the layer having high light scattering property contains at least semiconductor fine particles having an average particle size of 100 to 500 nm and has a medium light scattering property. Contains a mixture of semiconductor fine particles having an average particle diameter of 100 to 500 nm and semiconductor fine particles having an average particle diameter of 5 to 50 nm.

  In Patent Document 3, the light-incident side has a low light scattering property and a light scattering property becomes higher as the light travels than in the case where the photosensitive layer has a uniform single layer structure in the film thickness direction. In the case of, the light capture rate is higher and the conversion efficiency is higher.

  The light scattering property of the photosensitive layer can be adjusted by the type, particle diameter, porosity, or void size of the semiconductor fine particles used. Among these, it is preferable to adjust by the particle diameter of the semiconductor fine particles.

  Furthermore, when the photosensitive layer has a two-layer structure of a low scattering layer and a high scattering layer, it is preferable to mix two or more kinds of fine particles as constituents of the high scattering layer rather than using a single semiconductor fine particle. Specifically, the high scattering layer is particularly preferably a mixture of semiconductor fine particles having an average particle diameter of 5 to 50 nm and semiconductor fine particles having an average particle diameter of 100 to 500 nm. At this time, the content of the larger semiconductor fine particles is preferably 10 to 90% by weight, and more preferably 10 to 50% by weight.

  Furthermore, in the case of a three-layer structure of a low scattering layer, a medium scattering layer, and a high scattering layer, it is preferable that two or more kinds of fine particles are mixed in the medium scattering layer rather than using a single semiconductor fine particle. Specifically, the medium scattering layer is particularly preferably a mixture of semiconductor fine particles having an average particle diameter of 5 to 50 nm and semiconductor fine particles having an average particle diameter of 100 to 500 nm. At this time, the content of the larger semiconductor fine particles is preferably 5 to 70% by weight, more preferably 10 to 50% by weight.

  Further, in the case of four or more layers, a composition in which the light scattering rate increases from the low light scattering layer side toward the high light scattering layer is desirable. The high scattering layer may be a single semiconductor fine particle having an average particle diameter of 100 to 500 nm or a mixture of two or more kinds of semiconductor fine particles. When the high scattering layer is composed of a mixture of semiconductor fine particles having an average particle diameter of 5 to 50 nm and semiconductor fine particles having an average particle diameter of 100 to 500 nm, the mixing ratio is such that the content of the larger semiconductor fine particles is 30 to 100% by weight. It is preferable that it is 50 to 100 weight%. Moreover, the content rate of the larger semiconductor particle is larger than that of the middle scattering layer.

The sensitizing dye used in the photosensitive layer can be used in combination or mixed with two or more kinds of dyes in order to make the wavelength range of photoelectric conversion as wide as possible and increase the conversion efficiency. In this case, the dye to be used or mixed and the ratio thereof can be selected so as to match the wavelength range and intensity distribution of the target light source. Patent Document 3 describes that a dye-sensitized photoelectric conversion element having improved conversion efficiency than the conventional one is obtained.
JP-A-10-255863 JP 2001-93591 A JP 2002-222968 A Published by Information Technology Co., Ltd. “Frontiers and Future Prospects of Dye-Sensitized Solar Cells and Solar Cells” P26-P27

  When a single porous oxide semiconductor layer is used as in a conventional dye-sensitized solar cell, there is a problem in that light use efficiency is low and high conversion efficiency cannot be obtained. Therefore, the configuration of Patent Document 1 in which a light-reflecting particle layer is provided on the back surface of the porous oxide semiconductor layer, a plurality of porous oxide semiconductor layers having different fine particle sizes, Although there existed the structure of the patent documents 2 and 3 which mixed the large light-scattering particle | grains with the oxide semiconductor layer and made it function also as a scattering layer, there existed the following problems, respectively.

  The solar cell of Patent Document 1 has the following problems. The light reflecting particle layer is composed of high refractive material particles made of, for example, titanium oxide (rutile) having a particle size of about 200 to 500 nm. The thickness of the light reflecting particle layer is preferably about 5 to 10 μm. Thus, it is difficult to sinter particles having such a large particle size at about 500 ° C., film formation cannot be performed, and the resistance of the conductive path is large, so that the current from the dye cannot be taken out efficiently. Further, when the temperature is raised for sintering, the electrical resistance of the electrode and the transparent conductive layer is increased, and the conversion efficiency is lowered. In addition, since the particle size of the light reflecting particle layer is an order of magnitude larger than the particle size of the light absorbing particle layer, the surface area of the particles becomes 1/100, so the amount of adsorbed dye is extremely small and hardly contributes to the improvement of the conversion efficiency. . In addition, providing a light-reflecting particle layer thin film made of highly refractive material particles complicates the manufacturing process and increases the cost.

  The photoelectric conversion device of Patent Document 2 has the following problems. The average particle size of the fine particles in the vicinity of the transparent conductor layer is 5 to 50 nm, and the average particle size of the fine particles in the vicinity of the charge transport layer is 30 to 500 nm, which is larger. It is difficult to sinter at about 0 ° C., a film cannot be formed, and the resistance of the conductive path is so large that the current from the dye cannot be taken out efficiently. Further, when the temperature is raised for sintering, the electrical resistance of the electrode and the transparent conductor layer is increased, and the conversion efficiency is lowered. In addition, when fine particles with a large particle size are mixed with fine particles with a small particle size, dispersion becomes difficult and the paste cannot be prepared well, and coating for film formation becomes difficult. Further, since the particle size of the light reflecting particle layer is an order of magnitude larger than the particle size of the light absorbing particle layer, the surface area of the particles becomes 1/100, the amount of adsorbed dye is extremely small, and hardly contributes to the improvement of the conversion efficiency. In addition, it is not possible to photoelectrically convert light in a wide absorption wavelength range with one kind of dye.

  In the photoelectric conversion element of Patent Document 3, the light scattering property of the photosensitive layer can be adjusted by the type, particle diameter, porosity, or void size of the semiconductor fine particles to be used. However, there were the following problems. That is, preparing a particle having a large particle size such as semiconductor fine particles having an average particle size of 100 to 500 nm as a paste is difficult to prepare the paste because the dispersibility is lowered and the particles are likely to aggregate.

  In addition, it is difficult to sinter particles having a large particle size, such as semiconductor fine particles having an average particle size of 100 to 500 nm, at about 500 ° C., film formation is impossible, the resistance of the conductive path is large, and the current from the dye Cannot be taken out efficiently. Further, when the temperature is raised for sintering, the electrical resistance of the electrode and the transparent conductive layer is increased, and the conversion efficiency is lowered. Further, since the particle size of the high light scattering layer is one order of magnitude larger than the particle size of the low light scattering layer, the surface area of the particles is 1/100, the amount of adsorbed dye is extremely small, and hardly contributes to the improvement of the conversion efficiency. These problems are slightly reduced by mixing semiconductor fine particles having an average particle diameter of 5 to 50 nm and semiconductor fine particles having an average particle diameter of 100 to 500 nm, but these problems are not completely solved.

  Therefore, the present invention has been completed in view of the above-mentioned problems in the prior art, and the object thereof is as follows.

(1) When light scattering property is imparted to the light emitting side porous oxide semiconductor layer, light incident is performed without using scattering particles having an average particle size larger than that of the semiconductor fine particles of the light incident side porous oxide semiconductor layer. The above-described various problems are solved by using semiconductor fine particles having the same average particle diameter as the semiconductor fine particles of the porous oxide semiconductor layer on the light emitting side for the porous oxide semiconductor layer on the light emitting side.

(2) Even when semiconductor fine particles having a small average particle diameter are used in the porous oxide semiconductor layer on the light emitting side, light scattering properties can be imparted to the porous oxide semiconductor layer on the light emitting side.

(3) The firing temperature can be surely fired at the same low temperature in the porous oxide semiconductor layer on the light incident side and the porous oxide semiconductor layer on the light exit side.

(4) To increase the productivity and reliability of the porous oxide semiconductor layer on the light emitting side, to ensure the conductive path, and to increase the conversion efficiency.

(5) Even when the light emitting side porous oxide semiconductor layer is formed, the electrical resistance of the electrode and the transparent conductive layer should not be increased.

(6) The porous oxide semiconductor layer on the light emitting side is made of a porous body having sufficient porosity, and has a large surface area, thereby increasing the amount of dye adsorbed and converting light on the longer wavelength side. To contribute to efficiency.

(7) Increasing the film thickness of the porous oxide semiconductor layer on the light incident side with high light transmittance, increasing the adsorption amount of the dye to increase the conversion efficiency, and porous oxidation on the light emitting side with high light reflectivity Reducing the electrical resistance of the porous oxide semiconductor layer by reducing the thickness of the physical semiconductor layer.

(8) A porous oxide semiconductor layer that can impart light scattering properties to a light emitting side porous oxide semiconductor layer even if semiconductor fine particles having a small average particle diameter are used in the light emitting side porous oxide semiconductor layer Providing a manufacturing method.

  The photoelectric conversion device of the present invention is a dye-sensitized photoelectric conversion device in which a porous oxide semiconductor layer supporting a dye and an electrolyte layer are formed on a conductive substrate, wherein the porous oxide semiconductor layer includes a plurality of porous oxide semiconductor layers. And the arithmetic average roughness of the surface of the porous oxide semiconductor layer on the light incident side or the surface of the fracture surface is a surface of the porous oxide semiconductor layer on the light emission side or the surface of the fracture surface. The thickness of the porous oxide semiconductor layer on the light incident side is smaller than the thickness of the porous oxide semiconductor layer on the light emitting side.

  In the photoelectric conversion device of the present invention, preferably, the porous oxide semiconductor layer formed by laminating a plurality of layers is made of a sintered body of oxide semiconductor fine particles, and forms the porous oxide semiconductor layer on the light emitting side. The average particle size of the sintered particles of the oxide semiconductor fine particles is larger than the average particle size of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light incident side.

  A method for producing a photoelectric conversion device according to the present invention includes a porous oxide semiconductor layer formed of a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate and carries a dye, and an electrolyte layer In the method for producing a dye-sensitized photoelectric conversion device formed with a plurality of layers, an average particle size of primary particles before sintering of oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers Forming the porous oxide semiconductor layer with the same diameter and on the light incident side by applying and baking a colloidal liquid paste in which the dispersed phase is the primary particles of the oxide semiconductor fine particles and the dispersion medium is a liquid The porous oxide semiconductor layer on the light emitting side is formed by spraying and baking an aerosol obtained by adding a gas as a dispersion medium to the liquid paste.

  The method for producing a photoelectric conversion device of the present invention includes a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate and carrying a dye, and In the method for manufacturing a dye-sensitized photoelectric conversion device in which an electrolyte layer is formed, primary particles before sintering of oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers The porous oxide semiconductor layer on the light incident side having the same average particle diameter is coated with a colloidal liquid paste in which the dispersed phase is a primary particle of the oxide semiconductor fine particles and the dispersion medium is a liquid, and is fired. The porous oxide semiconductor layer on the light emission side is formed by applying and baking a liquid paste in which fine particles of an organic resin are added as a dispersed phase to the liquid paste.

  The method for producing a photoelectric conversion device of the present invention includes a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate and carrying a dye, and In the method for manufacturing a dye-sensitized photoelectric conversion device in which an electrolyte layer is formed, primary particles before sintering of oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers The porous oxide semiconductor layer on the light incident side having the same average particle diameter is coated with a colloidal liquid paste in which the dispersed phase is a primary particle of the oxide semiconductor fine particles and the dispersion medium is a liquid, and is fired. The porous oxide semiconductor layer on the light emission side is formed by spraying and baking an aerosol in which fine particles of an organic resin are added to the liquid paste as a dispersed phase and a gas is added as a dispersion medium. And wherein the Rukoto.

  The photovoltaic power generation device of the present invention is characterized in that the photoelectric conversion device of the present invention is used as a power generation means, and the generated power of the power generation means is supplied to a load.

  The photoelectric conversion device of the present invention is a dye-sensitized photoelectric conversion device in which a porous oxide semiconductor layer supporting a dye and an electrolyte layer are formed on a conductive substrate, and the porous oxide semiconductor layer includes a plurality of layers. The arithmetic average roughness of the surface of the porous oxide semiconductor layer on the light incident side or the surface of the fractured surface is the arithmetic average of the surface of the porous oxide semiconductor layer on the light output side or the surface of the fractured surface. Since the thickness of the porous oxide semiconductor layer on the light incident side is smaller than the roughness, and the thickness of the porous oxide semiconductor layer on the light output side is larger than that of the light incident side, the porous oxide semiconductor layer on the light incident side has a short wavelength. Light (400 to 600 nm) is well scattered and confined, but long wavelength light (600 to 900 nm) is well transmitted. Since long wavelength light is easily transmitted, it can be formed thick. Therefore, the dye carried by the porous oxide semiconductor layer on the light incident side absorbs short-wavelength light well, and since the arithmetic mean roughness is small, the surface area is increased, and the amount of dye carried increases. The photocurrent can be increased.

  The porous oxide semiconductor layer on the light emitting side scatters and confines long-wavelength light inside thereof and can be formed thin, so that the resistance of the conductive path can be reduced. Therefore, the long-wavelength light is well absorbed by the dye supported on the porous oxide semiconductor layer on the light emitting side, the photocurrent from the dye is increased, and the current from the dye can be efficiently extracted with low resistance. .

  Preferably, a porous oxide semiconductor layer is further provided between the light incident side and light emitting side porous oxide semiconductor layers, and the surface of the intermediate porous oxide semiconductor layer or the surface of the fracture surface is arithmetically operated. By setting the average roughness to an intermediate size, the intermediate wavelength light (550 to 650 nm) of the short wavelength light and the long wavelength light can be scattered and confined and supported by the intermediate porous oxide semiconductor layer. The intermediate wavelength light is well absorbed by the dye, and the photocurrent from the dye can be increased.

  In addition, when a photoelectric conversion device is manufactured by immersing a plurality of porous oxide semiconductor layers carrying a dye on a conductive substrate in a dye solution, the dye solution side is closer to the porous oxide semiconductor layer on the light incident side. The porous oxide semiconductor layer on the light emitting side has a larger arithmetic average roughness on the surface or the surface of the fracture surface, so that the penetration rate of the dye into the porous oxide semiconductor layer on the light emitting side and light incident side As a result, the dye can be reliably adsorbed (colored) to the porous oxide semiconductor layer on the light incident side.

  In the photoelectric conversion device of the present invention, preferably, the porous oxide semiconductor layer formed by laminating a plurality of layers is composed of a sintered body of oxide semiconductor fine particles, and the oxide semiconductor forming the porous oxide semiconductor layer on the light emission side Since the average particle size of the sintered particles of the fine particles is larger than the average particle size of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light incident side, the porous oxide semiconductor on the light incident side The layer scatters and confines the short wavelength light (400 to 600 nm) well, but transmits the long wavelength light (600 to 900 nm) well, and the layer can be formed thick because it easily transmits the long wavelength light. Therefore, the dye carried by the porous oxide semiconductor layer on the light incident side absorbs short-wavelength light well, and since the arithmetic mean roughness is small, the surface area is increased, and the amount of dye carried increases. The photocurrent can be increased.

  Moreover, since the porous oxide semiconductor layer on the light incident side and the porous oxide semiconductor layer on the light output side are composed of oxide semiconductor fine particles having the same particle size, the sintering temperature can be low and the sintering temperature must be high. As a result, there is no increase in resistance of the electrode and the transparent conductive layer, and the manufacturing process is simplified and the reliability of the product is increased.

  In addition, since the sintered particles (secondary particles) of the porous oxide semiconductor layer on the light emitting side are formed by firing aggregates of primary particles, the pores of the porous body become larger, and the amount of dye supported is increased. It is possible to increase the photocurrent.

  A method for producing a photoelectric conversion device according to the present invention includes a porous oxide semiconductor layer formed of a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate and carries a dye, and an electrolyte layer In the method for producing a dye-sensitized photoelectric conversion device formed with a plurality of layers, an average particle size of primary particles before sintering of oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers A porous oxide semiconductor layer having the same diameter and a light incident side is formed by applying and baking a colloidal liquid paste in which a dispersed phase is a primary particle of oxide semiconductor fine particles and a dispersion medium is a liquid, The oxide semiconductor that forms the porous oxide semiconductor layer on the light emitting side by forming the porous oxide semiconductor layer on the light emitting side by spray-coating and baking an aerosol obtained by adding a gas as a dispersion medium to the liquid paste. Fine particles Since the average particle size of the sintered particles can be made larger than the average particle size of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light incident side, the above-mentioned excellent effects are obtained. A photoelectric conversion device can be obtained.

  The method for producing a photoelectric conversion device of the present invention includes a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate and carrying a dye, and In the method for manufacturing a dye-sensitized photoelectric conversion device in which an electrolyte layer is formed, an average of primary particles before sintering of oxide semiconductor fine particles constituting each layer of a porous oxide semiconductor layer in which a plurality of layers are laminated A porous oxide semiconductor layer having the same particle size and having a light incident side is formed by applying and baking a colloidal liquid paste in which a dispersed phase is a primary particle of oxide semiconductor fine particles and a dispersion medium is a liquid. The porous oxide semiconductor layer on the light emitting side is formed by applying and baking a liquid paste in which fine particles of an organic resin are added as a dispersed phase to the liquid paste. Oxide half Since the average particle size of the sintered particles of the body fine particles can be made larger than the average particle size of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light incident side, the above excellent effect Can be obtained.

  The method for producing a photoelectric conversion device of the present invention includes a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate and carrying a dye, and In the method for manufacturing a dye-sensitized photoelectric conversion device in which an electrolyte layer is formed, an average of primary particles before sintering of oxide semiconductor fine particles constituting each layer of a porous oxide semiconductor layer in which a plurality of layers are laminated A porous oxide semiconductor layer having the same particle size and having a light incident side is formed by applying and baking a colloidal liquid paste in which a dispersed phase is a primary particle of oxide semiconductor fine particles and a dispersion medium is a liquid. The light emitting side porous oxide semiconductor layer is formed by spraying and baking an aerosol in which fine particles of organic resin are added as a dispersed phase and gas is added as a dispersion medium to a liquid paste, and then fired. The average particle diameter of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the side is larger than the average particle diameter of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light incident side. Since it can enlarge, the photoelectric conversion apparatus which has said outstanding effect can be obtained.

  The photovoltaic device of the present invention uses the photoelectric conversion device of the present invention as a power generation means, and supplies the generated power of the power generation means to a load. This is the operational effect of the photoelectric conversion device of the present invention. The porous oxide semiconductor layer carrying the light incident side dye scatters and absorbs short wavelength light well, and the porous oxide semiconductor layer carrying the light exit side dye scatters long wavelength light well. Then, it becomes a highly reliable photovoltaic device having high conversion efficiency utilizing the effect of confining and absorbing well, increasing the photocurrent and increasing the conversion efficiency.

  DESCRIPTION OF EMBODIMENTS Embodiments of a photoelectric conversion device, a manufacturing method thereof, and a photovoltaic device of the present invention will be described below in detail with reference to FIGS. In addition, in each figure, the same code | symbol is attached | subjected to the same member.

  A cross-sectional view of the photoelectric conversion device of the present invention is shown in FIG. The photoelectric conversion device 1 of FIG. 1 has a porous oxide semiconductor layer composed of two layers, and is a first porous oxide semiconductor formed on a conductive substrate 2 and adsorbing a dye (not shown). The layer 3 includes a second porous oxide semiconductor layer 4 that has adsorbed a dye, an electrolyte layer 7, a counter electrode 8, and a sealing portion 9.

  That is, the photoelectric conversion device 1 according to the present invention is a dye-sensitized photoelectric conversion device 1 in which the porous oxide semiconductor layers 3 and 4 and the electrolyte layer 7 supporting a dye are formed on a conductive substrate 2. The porous oxide semiconductor layers 3 and 4 are formed by laminating a plurality of layers, and the arithmetic average roughness of the surface of the porous oxide semiconductor layer 3 on the light incident side or the surface of the fracture surface is porous oxidation on the light emitting side. The thickness of the porous oxide semiconductor layer 3 on the light incident side is smaller than the arithmetic mean roughness of the surface of the physical semiconductor layer 4 or the surface of the fracture surface, and the thickness of the porous oxide semiconductor layer 4 on the light emitting side is thicker It is.

  In the present invention, regarding the arithmetic average roughness of the porous oxide semiconductor layers 3 and 4, the arithmetic average roughness of the surface (the upper surface and the lower surface of the layer) or the fracture surface thereof is determined between the light incident side and the light emitting side. Although the magnitude relation is defined, the arithmetic average roughness of at least the surfaces of the porous oxide semiconductor layers 3 and 4 may be the magnitude relation described above. That is, if the arithmetic average roughness of the surface of the porous oxide semiconductor layer 3 on the light incident side is smaller than the arithmetic average roughness of the surface of the porous oxide semiconductor layer 4 on the light emitting side, naturally, The arithmetic mean roughness of the surface of the fracture surface corresponding to the sintered surface of the porous oxide semiconductor layer 3 on the light incident side is that of the fracture surface corresponding to the sintered surface of the porous oxide semiconductor layer 4 on the light emission side. This is because it is considered to be smaller than the arithmetic average roughness of the surface.

  Further, the arithmetic average roughness of the surface of the porous oxide semiconductor layers 3 and 4 or the surface of the fractured surface is determined by measuring the surface of the porous oxide semiconductor layer 4 which is an exposed surface, etc. It can be measured with a needle type surface roughness measuring device), an atomic force microscope (AFM) or the like. Moreover, when measuring the surface of the torn surface of the porous oxide semiconductor layers 3 and 4, it is preferable to measure with an atomic force microscope. The porous oxide semiconductor layer 3 has a film thickness of 3 to 25 μm, more preferably 6 to 18 μm. The width (thickness) of the fracture surface is narrow, and a means that can be measured within a range of several μm is an atom. This is because the atomic force microscope (AFM) is excellent.

  In the method of manufacturing the photoelectric conversion device 1 in FIG. 1, the first porous oxide semiconductor layer 3 is applied and formed on the conductive substrate 2 and baked, and then the second porous oxide semiconductor layer 4 is formed. Then, the conductive substrate 2 is immersed in the dye solution to adsorb the dye to the porous oxide semiconductor layer, and then the outer periphery of the counter electrode 8 and the conductive substrate 2 is used as the sealing portion 9. Then, the electrolyte layer 7 is injected between the counter electrode 8 and the conductive substrate 2 to complete.

  That is, in the method for manufacturing the photoelectric conversion device 1 of the present invention, a porous oxide semiconductor layer comprising a sintered body of oxide semiconductor fine particles, which is formed by laminating a plurality of layers on a conductive substrate 2 and carrying a dye. In the method for manufacturing the dye-sensitized photoelectric conversion device 1 in which the electrolyte layers 7 and 3 and the electrolyte layer 7 are formed, the oxide semiconductors that constitute each of the porous oxide semiconductor layers 3 and 4 in which a plurality of layers are laminated The average particle diameter of the primary particles before sintering of the fine particles is the same, the porous oxide semiconductor layer 3 on the light incident side is colloidal in which the dispersed phase is the primary particles of the oxide semiconductor fine particles and the dispersion medium is a liquid. The light emitting side porous oxide semiconductor layer 4 is formed by spraying and baking an aerosol in which a gas is added as a dispersion medium to the light paste.

  In the method for manufacturing a photoelectric conversion device of the present invention, the average particle size of primary particles before sintering of oxide semiconductor fine particles constituting each layer of porous oxide semiconductor layers 3 and 4 formed by laminating a plurality of layers is The light incident side porous oxide semiconductor layer 3 is formed by applying and baking a colloidal liquid paste in which the dispersed phase is the primary particles of oxide semiconductor fine particles and the dispersion medium is a liquid. The emission-side porous oxide semiconductor layer 4 is formed by applying and baking a liquid paste in which fine particles of an organic resin are added as a dispersed phase to the liquid paste.

  In the method for manufacturing a photoelectric conversion device of the present invention, the average particle size of primary particles before sintering of oxide semiconductor fine particles constituting each layer of porous oxide semiconductor layers 3 and 4 formed by laminating a plurality of layers is The light incident side porous oxide semiconductor layer 3 is formed by applying and baking a colloidal liquid paste in which the dispersed phase is the primary particles of oxide semiconductor fine particles and the dispersion medium is a liquid. The emission-side porous oxide semiconductor layer 4 is formed by spraying and baking an aerosol in which fine particles of an organic resin are added as a dispersed phase to a liquid paste and a gas is added as a dispersion medium.

  Here, the firing of the first porous oxide semiconductor layer 3 is preliminarily fired (dried) at a low temperature, and then the second porous oxide semiconductor layer 4 is applied and formed, and then fired together. Also good.

  FIG. 2 shows a cross-sectional view of another example of the embodiment of the photoelectric conversion device of the present invention. The photoelectric conversion device 1 shown in FIG. 2 has a porous oxide semiconductor layer composed of three layers, and is formed on a conductive substrate 2 and is a first porous oxide semiconductor adsorbing a dye (not shown). Layer 3, second porous oxide semiconductor layer 4 that adsorbs the dye, third porous oxide semiconductor layer 5 that adsorbs the dye, electrolyte layer 7, counter electrode 8, and sealing portion 9. .

  2, the first porous oxide semiconductor layer 3 is applied and formed on the conductive substrate 2 and baked, and then the second porous oxide semiconductor layer 4 is formed. Coating and forming and baking, and then applying and baking the third porous oxide semiconductor layer 5, and then immersing the conductive substrate 2 in the dye solution to form the porous oxide semiconductor layers 3 to 5 The dye is adsorbed, and then the outer periphery of the counter electrode 8 and the conductive substrate 2 is sealed with the sealing portion 9, and then the electrolyte layer 7 is injected between the counter electrode 8 and the conductive substrate 2 to complete. .

  Next, each element which comprises the photoelectric conversion apparatus 1 mentioned above is demonstrated in detail.

<Conductive substrate>
As the conductive substrate 2, a substrate having a transparent conductive layer 2b on a light-transmitting substrate 2a is preferable. As a material of the substrate 2a, glass such as white plate glass, soda glass, borosilicate glass, or an inorganic material such as ceramics may withstand the firing temperature. The thickness of the substrate 2a is 0.05 to 8 mm, preferably 0.2 to 4 mm in terms of mechanical strength.

As the transparent conductive layer 2b, a transparent conductive layer of metal oxide doped with fluorine or metal is used. For example, an impurity (F, Sb, etc.)-Doped tin oxide film (SnO ₂ film), an impurity (Ga, Al, etc.)-Doped zinc oxide film (ZnO film), a tin-doped indium oxide film (ITO film) or an impurity-doped oxide An indium film (In ₂ O ₃ film), a niobium-doped titanium oxide film, or the like may be used.

Among these, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by thermal CVD or spray pyrolysis is best because it has heat resistance and low material cost. Examples of the method for forming the transparent conductive layer 2b include a thermal CVD method, a spray pyrolysis method, a sputtering method, a vacuum deposition method, an ion plating method, a dip coating method, a solution growth method, and a sol-gel method.

  The thickness of the transparent conductive layer 2b is 0.001 to 10 μm, preferably 0.05 to 2.0 μm.

  Further, the transparent conductive layer 2b may be an extremely thin metal film such as Au, Pd, or Al formed by a vacuum deposition method or a sputtering method. Further, these metal films may be laminated and used in various combinations. For example, as the transparent conductive layer 2b, a Ti layer, an ITO layer, and a Ti layer may be sequentially laminated, and a laminated film with improved adhesion and corrosion resistance is obtained.

  Further, the substrate 2a of the conductive substrate 2 may be non-translucent when light is incident from the opposite direction (upper side in FIG. 1), a thin metal sheet made of titanium, stainless steel, nickel or the like, or carbon In order to prevent corrosion of the electrolyte layer 7 by the electrolyte, a thin sheet made of an insulating substrate or the like may be coated with a titanium layer, a stainless steel layer, a conductive metal oxide layer, or the like.

  In the present invention, the porous oxide semiconductor layers 3, 4, 5 are fired (400 ° C. to 550 ° C.), so that the porous oxide semiconductor layers 3, 4, 5 are directly formed on a resin substrate having low heat resistance. I can't. In such a case, the porous oxide semiconductor layers 3, 4, 5 are first formed and fired on a heat-resistant support substrate (a metal sheet such as aluminum), and then the transparent conductive layer 2 b is formed or the transparent conductive layer 2 b is formed. The porous oxide semiconductor films 3, 4 and 5 may be transferred and bonded onto the substrate 2a made of the coated resin, and then the supporting substrate may be peeled off.

  The material of the substrate 2a made of resin is preferably a material such as polycarbonate (PC), acrylic resin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, or the like. With such a transfer mold manufacturing method, the low-cost substrate 2a can be used, and flexibility (flexibility) can be imparted to the substrate 2a. Considering the substrate 2a made of resin, the thickness of the conductive substrate 2 is 0.005 to 5 mm, preferably 0.01 to 2 mm in terms of mechanical strength.

<Porous oxide semiconductor layer>
As the porous oxide semiconductor layers 3, 4 and 5, a porous n-type oxide semiconductor layer made of titanium dioxide or the like is preferable. As shown in FIGS. 1 and 2, porous oxide semiconductor layers 3 and 4 or porous oxide semiconductor layers 3 to 5 are sequentially formed on a conductive substrate 2.

As the material and composition of the porous oxide semiconductor layers 3 to 5, titanium oxide (TiO ₂ ) is optimal, and as other materials, titanium (Ti), zinc (Zn), tin (Sn), niobium ( Nb), indium (In), yttrium (Y), lanthanum (La), zirconium (Zr), tantalum (Ta), hafnium (Hf), strontium (Sr), barium (Ba), calcium (Ca), vanadium ( V), at least one metal oxide semiconductor of a metal element such as tungsten (W) is preferable, and nitrogen (N), carbon (C), fluorine (F), sulfur (S), chlorine (Cl), You may contain 1 or more types of nonmetallic elements, such as phosphorus (P). Titanium oxide or the like is preferable because it has an electron energy band gap in the range of 2 to 5 eV that is larger than the energy of visible light. The porous oxide semiconductor layers 3 to 5 are preferably n-type semiconductors whose conduction band is lower than the conduction band of the dye in the electron energy level.

  The porous oxide semiconductor layers 3 to 5 are all composed of oxide semiconductor fine particles having the same primary particles, and the average particle size of the primary particles is preferably 1 to 40 nm, and more preferably 5 to 30 nm. Here, if the lower limit value 1 nm of the average particle diameter is less than this, the material cannot be refined, and if the upper limit value 40 nm is exceeded, the junction area is reduced and the photocurrent is significantly reduced.

  The porous oxide semiconductor layers 3 to 5 of the present invention are prepared by using a fine primary oxide semiconductor fine particle as a dispersion phase, and preparing a paste using an aqueous or non-aqueous solution as a dispersion medium. Are sequentially applied and fired on the conductive substrate 2. In this way, by forming the porous oxide semiconductor layers 3 to 5 with a fine oxide semiconductor and making them porous, the surface area of all the porous oxide semiconductor layers 3 to 5 as the photoactive electrode layer is increased. Therefore, light absorption, photoelectric conversion, and electron conduction can be performed efficiently.

  The porous oxide semiconductor layer 3 on the light incident side preferably has an arithmetic average roughness Ra of 10 to 60 nm, more preferably 15 to 55 nm, on the surface after firing or the surface of the fracture surface. . The porous oxide semiconductor layer 3 should be transparent when viewed under visible light. Since the porous oxide semiconductor layer 3 on the light incident side has a small arithmetic average roughness Ra after sintering, it scatters and confines short wavelength light (400 to 600 nm) well, but long wavelength light (600 to 900 nm). Can be formed thick because long wavelength light is easily transmitted. Therefore, the short wavelength light is well absorbed by the dye supported on the porous oxide semiconductor layer 3, and the amount of the dye supported is large, so that the photocurrent from the dye can be increased.

In order to form the porous oxide semiconductor layer 3 on the light incident side, first, a liquid paste is prepared. The liquid paste is prepared, for example, by adding acetylacetone to TiO ₂ anatase powder, kneading with deionized water, and preparing a titanium oxide paste stabilized with a surfactant. Before applying the prepared paste, centrifugal defoaming and vacuum degassing are performed to make a liquid paste that does not contain bubbles, and then this liquid paste is gently dropped on the conductive substrate 2, and the doctor blade method and bar coating method. Alternatively, it may be applied uniformly and gently at a constant speed by a spinner coater method or the like.

  Next, the porous oxide semiconductor layer 3 is formed by heat treatment in the atmosphere at 300 to 600 ° C., preferably 400 to 500 ° C., for 10 to 60 minutes, preferably 20 to 40 minutes. The thickness of the porous oxide semiconductor layer 3 on the light incident side is preferably 3 to 25 μm, and more preferably 6 to 18 μm.

  The porous oxide semiconductor layer 4 on the light emitting side may have an arithmetic average roughness Ra of 30 to 200 nm, more preferably 40 to 150 nm, on the surface after firing or the surface of the fracture surface. . The porous oxide semiconductor layer 4 should appear opaque when viewed under visible light. Due to such surface roughness after sintering, the porous oxide semiconductor layer 4 on the light emitting side scatters and confines long-wavelength light inside thereof and can be formed thin, so that the conductive path Resistance can be reduced. Therefore, the long wavelength light is well absorbed by the dye carried by the porous oxide semiconductor layer 4 on the light emitting side, the photocurrent from the dye is increased, and the current from the dye can be efficiently extracted with low resistance. .

  In order to form the porous oxide semiconductor layer 4, a liquid paste preparation method and a coating film formation method are used, and the following three methods are particularly preferable.

  In the first method, a liquid paste is first prepared in the same manner as in the case of the porous oxide semiconductor layer 3. This liquid paste is centrifugally defoamed to obtain a liquid paste containing no bubbles. Next, using a spray coating method or the like on the conductive substrate 2, it is dropped onto the conductive substrate 2 as a liquid paste containing bubbles and applied uniformly.

  In the second method, when a liquid paste is first prepared in the same manner as described above, organic resin fine particles are mixed and kneaded, and the prepared paste is centrifugally defoamed to obtain a liquid paste containing no bubbles. Next, this liquid paste is dropped onto the conductive substrate 2 and uniformly and uniformly applied by a doctor blade method, a bar coat method, a spinner coater method or the like.

  In the third method, a liquid paste is produced in the same manner as the second method. Next, this liquid paste is dropped onto the conductive substrate 2 as a liquid paste containing bubbles using a spray coating method or the like, and uniformly applied.

  As the organic resin fine particles used in the second and third methods, spherical fine particles of acrylic resin (methacrylic ester copolymer) are particularly good, and PEG (polyethylene glycol) flakes may be used.

  Thus, the coating film obtained by any one of the first to third methods is 300 to 600 ° C., preferably 400 to 500 ° C. in the atmosphere, and 10 to 60 minutes, preferably 20 to 40 in the atmosphere. By performing the partial heat treatment, the porous oxide semiconductor layer 4 is obtained. The porous oxide semiconductor layer 4 should be opaque by visual observation under visible light.

  Here, in the first method, the dispersed bubbles give the porous oxide semiconductor layer 4 a desired surface roughness, and in the second method, the dispersed organic resin fine particles are vaporized by firing to form a porous oxide semiconductor. In the third method, a desired surface roughness is given to the layer 4, and dispersed bubbles give part of the desired surface roughness to the porous oxide semiconductor layer 4, and fine particles of the dispersed organic resin are removed by firing. To give part of the desired surface roughness.

  The thickness of the porous oxide semiconductor layer 4 is preferably 1 to 12 μm, more preferably 2 to 10 μm, and can be formed thinner than the porous oxide semiconductor film 3.

  The porous oxide semiconductor layer 5 is provided between the light incident side and light emitting side porous oxide semiconductor layers 3 and 4, and the arithmetic average roughness of the surface after firing or the surface of the fracture surface Ra is preferably 20 to 120 nm, and more preferably 30 to 100 nm. The intermediate porous oxide semiconductor layer 5 should look translucent when viewed under visible light. The method for producing the porous oxide semiconductor layer 5 may be performed in substantially the same manner as the first to third methods described above. The paste viscosity may be adjusted to a lower value, or the mixing amount of organic resin fine particles may be reduced. Thus, the surface roughness Ra after firing can be set to an intermediate size.

  The intermediate wavelength light (550 to 650 nm) of short wavelength light and long wavelength light is scattered by setting the arithmetic average roughness of the surface of the porous oxide semiconductor layer 5 or the surface of the fractured surface to an intermediate size after sintering. Thus, the intermediate wavelength light is well absorbed by the dye supported on the porous oxide semiconductor layer 5 and the photocurrent from the dye can be increased.

  The film thickness of the porous oxide semiconductor layer 5 is preferably 1 to 10 μm, more preferably 3 to 8 μm, which is thinner than the porous oxide semiconductor film 3 and thicker than the porous oxide semiconductor film 4.

The graph of FIG. 3 shows the relationship between the surface roughness Ra of the porous oxide semiconductor layer made of TiO ₂ thus obtained and the absorption wavelength. Here, arithmetic average roughness Ra was evaluated based on JIS standard B0601-1994 with a surf test apparatus (product name “SJ-400” manufactured by Mitutoyo Corporation). The absorption wavelength was evaluated by determining the absorption peak wavelength of the light spectrum absorbed by the porous oxide semiconductor layer from the difference in light transmittance before and after forming the porous oxide semiconductor layer on the conductive substrate 2.

  FIG. 3 shows that the absorption wavelength is substantially proportional to Ra of the porous oxide semiconductor layer. Therefore, the absorption wavelength can be controlled by adjusting Ra of the porous oxide semiconductor layer as in the present invention.

Further, when the surface of the porous oxide semiconductor layers 3 to 5 is treated with TiCl ₄ , that is, immersed in a TiCl ₄ solution for about 10 hours, washed with water, and baked at 450 ° C. for 30 minutes, the electronic conductivity is increased. Improves the conversion efficiency.

  In addition, an extremely thin dense layer of an n-type oxide semiconductor may be inserted between the porous oxide semiconductor layer 3 and the conductive substrate 2, and the reverse current can be suppressed, so that the conversion efficiency is increased.

<Dye>
Examples of the sensitizing dye include a ruthenium-tris, ruthenium-bis, osmium-tris, osmium-bis transition metal complex, a polynuclear complex, or a ruthenium-cis-diaqua-bipyridyl complex, or a phthalocyanine or porphyrin. Xanthene dyes such as polycyclic aromatic compounds and rhodamine B are preferred.

  In order to adsorb the dye to the porous oxide semiconductor layers 3 to 5, the dye has at least one carboxyl group, sulfonyl group, hydroxamic acid group, alkoxy group, aryl group, phosphoryl group as a substituent. It is valid. Here, the substituent can strongly chemisorb the dye itself to the porous oxide semiconductor layers 3 to 5 and can easily transfer charges from the excited state dye to the porous oxide semiconductor layers 3 to 5. I just need it.

Examples of the method of adsorbing the dye on the porous oxide semiconductor layers 3 to 5 include a method of immersing the porous oxide semiconductor layers 3 to 5 formed on the conductive substrate 2 in a solution in which the dye is dissolved. It is done. Examples of the solvent of the solution for dissolving the dye include a mixture of one or more alcohols such as ethanol, ketones such as acetone, ethers such as diethyl ether, nitrogen compounds such as acetonitrile, and the like. The dye concentration in the solution is preferably about 5 × 10 ⁻⁵ to 2 × 10 ⁻³ mol / l (l (liter): 1000 cm ³ ).

  When the conductive substrate 2 on which the porous oxide semiconductor layers 3 to 5 are formed is immersed in the solution in which the dye is dissolved, the temperature conditions of the solution and the atmosphere are not particularly limited, and for example, under atmospheric pressure or vacuum Among these, room temperature or conditions for heating the conductive substrate 2 may be mentioned. The immersion time can be appropriately adjusted depending on the type of the dye and the solution, the concentration of the solution, and the like. Thereby, a pigment | dye can be made to adsorb | suck to the porous oxide semiconductor layers 3-5.

<Counter electrode>
As the counter electrode 8, a very thin film of platinum, carbon or the like having a catalytic function is preferable. In addition, an electrodeposited ultrathin film of gold (Au), palladium (Pd), aluminum (Al) or the like is preferable. Moreover, the thin film which consists of an electroconductive organic material is mentioned. Further, a porous film made of fine particles of these materials, for example, a porous film of carbon fine particles, etc. is good, the surface area of the counter electrode 8 is increased, and the electrolyte component of the electrolyte layer 7 can be contained in the pores, and the conversion efficiency Can be increased. It is possible to form the counter electrode 8 with only a thin film and integrate it on the conductive substrate 2 side, or to thicken the counter electrode 8 so that the counter electrode substrate as a support is not used. Using a counter electrode substrate provided with a catalyst layer made of Pt or the like may be easily manufactured.

When the counter electrode 8 includes a catalyst layer and a counter electrode substrate (not shown), the same substrate as the conductive substrate 2 can be used as the counter electrode substrate. For example, the counter electrode substrate is preferably made of a metal having low electrical resistance and excellent corrosion resistance, and for example, a metal sheet such as titanium or stainless steel is preferable. Alternatively, a resin substrate coated with a conductive layer may be used. Such a resin substrate is preferably a sheet of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polycarbonate or the like, and a metal thin film such as titanium or stainless steel is preferable as the conductive layer. Furthermore, a conductive metal oxide layer (ITO film, SnO ₂ : F film, ZnO: Al film, etc.) is provided between the metal sheet or the resin sheet with a conductive layer and the catalyst layer to prevent corrosion. If provided, reliability is increased. The thickness of these counter electrode substrates is 0.01 to 5 mm, preferably 0.1 to 3 mm in terms of mechanical strength.

<Sealing part>
1 and 2, the sealing portion 9 constituting the side wall of the photoelectric conversion device 1 provides mechanical strength that can prevent the electrolyte component of the electrolyte layer 7 from leaking to the outside, and directly with the external environment. It is provided to contact and protect the inside of the photoelectric conversion device 1 and prevent the photoelectric conversion function from deteriorating.

  The material of the sealing portion 9 is preferably a material having a moisture absorption preventing function and sufficient adhesive strength, such as ethylene vinyl acetate copolymer resin (EVA), polyvinyl butyral (PVB), ethylene-ethyl acrylate copolymer ( EEA), fluorine resin, epoxy resin, acrylic resin, saturated polyester resin, amino resin, phenol resin, polyamideimide resin, UV curable resin, silicone resin, fluorine resin, urethane resin, coating resin used for metal roof, etc. are good .

  The thickness of the sealing part 9 is 0.01 μm to 6 mm, preferably 1 μm to 4 mm. In addition, antiglare, heat shield, heat resistance, low contamination, antibacterial, antifungal, design, high workability, rust and abrasion resistance, snow sliding, antistatic, far infrared radiation, acid resistance By providing the sealing part 9 with properties, corrosion resistance, environmental compatibility, and the like, reliability and merchantability can be further improved.

<Electrolyte layer>
Examples of the electrolyte layer 7 include electrolyte solutions, gel electrolytes, ion conductive electrolytes such as solid electrolytes, and organic hole transport agents.

  As the electrolyte solution, a quaternary ammonium salt, a Li salt, or the like is used. As the composition of the electrolyte solution, for example, a solution prepared by mixing tetrapropylammonium iodide, lithium iodide, iodine or the like with ethylene carbonate, acetonitrile, methoxypropionitrile, or the like can be used.

  Gel electrolytes are roughly classified into chemical gels and physical gels. A chemical gel is a gel formed by a chemical bond by a cross-linking reaction or the like, and a physical gel is gelled near room temperature by a physical interaction. The gel electrolyte is a gel obtained by mixing a host polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyacrylic acid, or polyacrylamide into acetonitrile, ethylene carbonate, propylene carbonate, or a mixture thereof. An electrolyte is preferred. When using a gel electrolyte or a solid electrolyte, a low-viscosity precursor is contained in the porous oxide semiconductor layers 3 to 5, and two-dimensional or three-dimensional crosslinking is performed by means such as heating, ultraviolet irradiation, or electron beam irradiation. It can be gelled or solidified by reacting.

  As the ion conductive solid electrolyte, a solid electrolyte having a polymer chain such as polyethylene oxide, polyethylene oxide or polyethylene having a salt such as sulfonimidazolium salt, tetracyanoquinodimethane salt or dicyanoquinodiimine salt is preferable. As the molten salt of iodide, an iodide such as an imidazolium salt, a quaternary ammonium salt, an isoxazolidinium salt, an isothiazolidinium salt, a pyrazolidium salt, a pyrrolidinium salt, or a pyridinium salt can be used.

  Examples of the molten salt of iodide include 1,1-dimethylimidazolium iodide, 1, methyl-3-ethylimidazolium iodide, 1-methyl-3-pentylimidazolium iodide, 1-methyl- 3-isopentylimidazolium iodide, 1-methyl-3-hexylimidazolium iodide, 1-methyl-3-ethylimidazolium iodide, 1,2-dimethyl-3-propylimidazole iodide, 1-ethyl- Examples thereof include 3-isopropylimidazolium iodide and pyrrolidinium iodide.

  The photoelectric conversion apparatus 1 can be used as a power generation means, and a photovoltaic power generation apparatus configured to supply generated power from the power generation means to a load can be obtained. In other words, when one or a plurality of the photoelectric conversion devices 1 are used, a series, parallel or series-parallel connection is used as a power generation means, and the generated power is directly supplied from this power generation means to the DC load. May be. In addition, after the power generation means converts the generated power to appropriate AC power via power conversion means such as an inverter, it is possible to supply this AC power to an AC load such as a commercial power system or various electric devices. It is good also as a simple photovoltaic device. Furthermore, it is possible to use such a photovoltaic power generation device as a photovoltaic power generation device such as a photovoltaic power generation system in various aspects by installing it in a building with good sunlight, which enables high conversion efficiency and durability. A photovoltaic device can be provided.

  Further, the photovoltaic power generation apparatus of the present invention uses the photoelectric conversion apparatus 1 of the present invention as a power generation means and supplies the generated power of the power generation means to a load. It has the effects of increasing the reliability, increasing the application, expanding the use, and facilitating the manufacturing and reducing the cost. Moreover, the photoelectric conversion apparatus 1 of this invention is not limited to a solar cell as the use, It can apply if it has a photoelectric conversion function, and can also apply it to various light receiving elements, an optical sensor, etc.

  Example 1 of the photoelectric conversion device of the present invention will be described below. A photoelectric conversion device 1 having the configuration shown in FIG. 1 was produced as follows.

First, a glass substrate (3 cm long × 2 cm wide) with a transparent conductive layer made of fluorine-doped tin oxide was used as the conductive substrate 2. On the conductive substrate 2, a light incident side porous oxide semiconductor layer 3 made of titanium dioxide was formed. This porous oxide semiconductor layer 3 was formed as follows. First, acetylacetone was added to TiO ₂ anatase powder, and then kneaded with deionized water to prepare a liquid paste of titanium oxide stabilized with a surfactant. Next, bubbles of the liquid paste were eliminated with a centrifugal defoaming device and a vacuum device. This liquid paste was gently dropped onto the conductive substrate 2, applied by a bar coating method, and baked at 450 ° C. for 30 minutes in the air to form a porous oxide semiconductor layer 3 having a thickness of about 7 μm. When the surface of the porous oxide semiconductor layer 3 was measured for the arithmetic average roughness Ra of the surface of the porous oxide semiconductor layer 3 with a surf test apparatus, Ra = 18 nm, which was transparent under visual light. It was.

Next, the light emitting side porous oxide semiconductor layer 4 made of titanium dioxide was formed on the porous oxide semiconductor layer 3. This porous oxide semiconductor layer 4 was formed as follows. First, acetylacetone was added to TiO ₂ anatase powder, and then kneaded with deionized water to prepare a liquid paste of titanium oxide stabilized with a surfactant. Next, bubbles of the liquid paste were eliminated with a centrifugal defoamer. This liquid paste was uniformly coated on the porous oxide semiconductor layer 3 as a liquid paste containing bubbles by spray coating. Next, the porous oxide semiconductor layer 4 having a thickness of about 4 μm was formed by firing at 450 ° C. for 30 minutes in the air. When the surface of the surface of the porous oxide semiconductor layer 4 was measured with a surf test apparatus, the surface of the porous oxide semiconductor layer 4 was Ra = 84 nm, and was visually opaque under visible light.

  A conductive substrate 2 in which porous oxide semiconductor layers 3 and 4 are laminated, a dye obtained by dissolving a ruthenium complex dye N719 (manufactured by Solaronics SA) in acetonitrile and t-butanol (1: 1 by volume) as solvents. The dye was supported on the porous oxide semiconductor layers 3 and 4 by immersing in a solution (0.3 mmol / l) for 12 hours. Thereafter, the porous oxide semiconductor layers 3 and 4 were washed with ethanol and dried to produce a light working electrode side substrate composed of the conductive substrate 2 and the porous oxide semiconductor layers 3 and 4 carrying the dye.

  Next, a glass substrate with a transparent conductive layer made of fluorine-doped tin oxide was used for the counter electrode side substrate. On this transparent conductive layer, a Pt layer as a catalyst layer was formed to a thickness of 50 nm by sputtering, and this was used as a counter electrode side substrate.

These optical working electrode side substrate and counter electrode side substrate are arranged so that the porous oxide semiconductor layers 3 and 4 and the catalyst layer face each other, and an olefin resin formed in a frame shape on the outer periphery of these substrates Both substrates were pressed and sealed by sandwiching a sealing portion 9 made of (Mitsui / DuPont Polychemical Co., Ltd., trade name “Himiran”). And electrolyte was inject | poured through the through-hole of the counter electrode side board | substrate opened beforehand. In Example 1, the electrolyte was prepared using iodine (I ₂ ), lithium iodide (LiI), and acetonitrile solution, which are liquid electrolytes.

When the photoelectric conversion characteristics of the photoelectric conversion device thus obtained were evaluated, the conversion efficiency was 5.1% at AM 1.5 and 100 mW / cm ² .

  As described above, in Example 1, the photoelectric conversion device 1 of the present invention could be easily produced, and high conversion efficiency could be realized.

  Example 2 of the photoelectric conversion device of the present invention will be described below. A photoelectric conversion device 1 having the configuration shown in FIG. 1 was produced as follows.

  First, a glass substrate (3 cm long × 2 cm wide) with a transparent conductive layer made of fluorine-doped tin oxide was used as the conductive substrate 2. On the conductive substrate 2, a light incident side porous oxide semiconductor layer 3 made of titanium dioxide was formed. The porous oxide semiconductor layer 3 was formed in the same manner as in Example 1, and the porous oxide semiconductor layer 3 having a thickness of about 7 μm was formed. When the surface of the porous oxide semiconductor layer 3 was measured for Ra of the porous oxide semiconductor layer 3 with a surf test apparatus, Ra was 20 nm, and the surface was transparent under visible light.

  When the conductive substrate 2 on which the porous oxide semiconductor layer 4 was formed was broken and AFM measurement of the fracture surface of the porous oxide semiconductor layer 4 was performed in the range of 5 μm, Ra = 22 nm, A value almost the same as the value measured with the test apparatus (Ra = 20 nm) was obtained.

Next, the light emitting side porous oxide semiconductor layer 4 made of titanium dioxide was formed on the porous oxide semiconductor layer 3. This porous oxide semiconductor layer 4 was formed as follows. First, 10% by weight of spherical fine particles (average particle size 0.15 μm) of acrylic resin (methacrylic ester copolymer) was added to TiO ₂ anatase powder, and then kneaded with deionized water to prepare a titanium oxide liquid paste. Produced. Next, bubbles of the liquid paste were eliminated with a centrifugal defoamer. This liquid paste is gently dropped onto the porous oxide semiconductor layer 3 and applied by a bar coating method, followed by baking at 450 ° C. for 30 minutes in the air to form a porous oxide semiconductor layer 4 having a thickness of about 5 μm. Formed. When the surface of the porous oxide semiconductor layer 4 was measured with a surf test apparatus, Ra of the porous oxide semiconductor layer 4 was Ra = 62 nm, and was visually opaque under visible light.

  Next, the conductive substrate 2 on which the porous oxide semiconductor layers 3 and 4 are formed is dipped in a dye solution for 12 hours in the same manner as in Example 1 to carry the dye on the porous oxide semiconductor layers 3 and 4. And washed and dried to produce a photo-active electrode side substrate.

  Next, the same substrate as Example 1 was produced as a counter electrode side substrate.

The optical working electrode side substrate and the counter electrode side substrate are arranged so that the porous oxide semiconductor layers 3 and 4 and the catalyst layer face each other, and are formed in a frame shape on the outer periphery of the substrates. Both substrates were pressed against each other with the same sealing portion 9 as that of No. 1 and sealed by heating. And the electrolyte similar to the said Example 1 was inject | poured through the through-hole of the counter electrode side board | substrate opened beforehand. When the photoelectric conversion characteristics of the photoelectric conversion device thus obtained were evaluated, the conversion efficiency was 5.5% at AM 1.5 and 100 mW / cm ² .

  As described above, in Example 2, the photoelectric conversion device 1 of the present invention could be easily produced, and high conversion efficiency could be realized.

  Example 3 of the photoelectric conversion device of the present invention will be described below. The photoelectric conversion device 1 having the configuration shown in FIG. 2 was produced as follows.

  First, a glass substrate (3 cm long × 2 cm wide) with a transparent conductive layer made of fluorine-doped tin oxide was used as the conductive substrate 2. On the conductive substrate 2, a light incident side porous oxide semiconductor layer 3 made of titanium dioxide was formed. The porous oxide semiconductor layer 3 was formed in the same manner as in Example 1, and the porous oxide semiconductor layer 3 having a thickness of about 7 μm was formed. When the surface of the porous oxide semiconductor layer 3 was measured for Ra of the porous oxide semiconductor layer 3 with a surf test apparatus, Ra was 21 nm, and the surface was transparent under visible light.

Next, an intermediate porous oxide semiconductor layer 5 made of titanium dioxide was formed on the porous oxide semiconductor layer 3. This porous oxide semiconductor layer 5 was formed as follows. First, 5 wt% of acrylic resin (methacrylic acid ester copolymer) spherical fine particles (average particle size 0.15 μm) were added to TiO ₂ anatase powder, and then kneaded with deionized water to prepare a titanium dioxide liquid paste. Produced. Next, bubbles of the liquid paste were eliminated with a centrifugal defoamer. This liquid paste was gently dropped onto the porous oxide semiconductor layer 3 and applied by a bar coating method. Next, the porous oxide semiconductor layer 5 having a thickness of about 4 μm was obtained by baking at 450 ° C. for 30 minutes in the air. When the surface of the porous oxide semiconductor layer 5 was measured with a surf test apparatus, Ra of the porous oxide semiconductor layer 5 was Ra = 48 nm, and it was translucent when viewed under visible light.

Next, a light emitting side porous oxide semiconductor layer 4 made of titanium dioxide was formed on the porous oxide semiconductor layer 5. This porous oxide semiconductor layer 4 was formed as follows. First, 10% by weight of spherical fine particles (average particle size: 1.5 μm) of acrylic resin (methacrylic ester copolymer) was added to TiO ₂ anatase powder, and then kneaded with deionized water to prepare a liquid paste of titanium oxide. Produced. Next, bubbles of the liquid paste were eliminated with a centrifugal defoamer. This liquid paste was uniformly applied on the porous oxide semiconductor layer 5 as a liquid paste containing bubbles by spray coating. Next, the porous oxide semiconductor layer 5 having a thickness of about 2 μm was formed by baking at 450 ° C. for 30 minutes in the atmosphere. When the surface of the porous oxide semiconductor layer 4 was measured for Ra of the porous oxide semiconductor layer 5 with a surf test apparatus, Ra was 110 nm, and it was opaque by visual observation under visible light.

  The conductive substrate 2 on which the porous oxide semiconductor layers 3 to 5 are formed is dipped in a dye solution for 15 hours in the same manner as in Example 1 to carry the dye on the porous oxide semiconductor layers 3 to 5 and washed. And dried to prepare a photo-active electrode side substrate.

  Next, the same substrate as Example 1 was produced as a counter electrode side substrate.

The optical working electrode side substrate and the counter electrode side substrate are arranged so that the porous oxide semiconductor layers 3 to 5 and the catalyst layer face each other, and are formed in a frame shape on the outer peripheral portion of these substrates. Both substrates were pressed and heated to be sealed with a sealing portion 9 similar to 1 sandwiched therebetween. And the electrolyte similar to the said Example 1 was inject | poured through the through-hole of the counter electrode side board | substrate opened beforehand. When the photoelectric conversion characteristics of the photoelectric conversion device thus obtained were evaluated, the conversion efficiency was 5.7% at AM 1.5 and 100 mW / cm ² .

  As described above, in Example 3, the photoelectric conversion device 1 of the present invention could be easily produced, and high conversion efficiency could be realized.

It is sectional drawing which shows an example of embodiment about the photoelectric conversion apparatus of this invention. It is sectional drawing which shows the other example of embodiment about the photoelectric conversion apparatus of this invention. It is a graph which shows the relationship between the arithmetic mean roughness of the surface of a porous oxide semiconductor layer, and the absorption wavelength of the light absorbed by a porous oxide semiconductor layer.

Explanation of symbols

1: Photoelectric conversion device 2: Conductive substrate 3: Porous oxide semiconductor layer on light incident side 4: Porous oxide semiconductor layer on light emitting side 5: Intermediate porous oxide semiconductor layer 7: Electrolyte layer 8: Counter electrode 9: Sealing part

Claims (6)

  In a dye-sensitized photoelectric conversion device in which a porous oxide semiconductor layer supporting a dye and an electrolyte layer are formed on a conductive substrate, the porous oxide semiconductor layer is formed by laminating a plurality of layers, The arithmetic average roughness of the surface of the porous oxide semiconductor layer on the light incident side or the surface of the fracture surface is smaller than the arithmetic average roughness of the surface of the porous oxide semiconductor layer on the light emission side or the surface of the fracture surface, A photoelectric conversion device, wherein the thickness of the porous oxide semiconductor layer on the light incident side is thicker than the thickness of the porous oxide semiconductor layer on the light emission side.   The porous oxide semiconductor layer formed by laminating a plurality of layers is composed of a sintered body of oxide semiconductor fine particles, and an average of the sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light emission side. 2. The photoelectric conversion device according to claim 1, wherein a particle diameter is larger than an average particle diameter of sintered particles of the oxide semiconductor fine particles forming the porous oxide semiconductor layer on the light incident side.   A dye-sensitized photoelectric conversion in which a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles and an electrolyte layer are formed by laminating a plurality of layers and supporting a dye on a conductive substrate. In the device manufacturing method, the average particle diameter of the primary particles before sintering of the oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers is the same, and A porous oxide semiconductor layer is formed by applying and baking a colloidal liquid paste in which a dispersed phase is a primary particle of the oxide semiconductor fine particles and a dispersion medium is a liquid, and the porous oxide on the light emitting side is formed. A method for producing a photoelectric conversion device, wherein the semiconductor layer is formed by spraying and baking an aerosol obtained by adding a gas as a dispersion medium to the liquid paste.   A dye-sensitized photoelectric conversion in which a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles and an electrolyte layer are formed by laminating a plurality of layers and supporting a dye on a conductive substrate. In the device manufacturing method, the average particle diameter of the primary particles before sintering of the oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers is the same, and A porous oxide semiconductor layer is formed by applying and baking a colloidal liquid paste in which a dispersed phase is a primary particle of the oxide semiconductor fine particles and a dispersion medium is a liquid, and the porous oxide on the light emitting side is formed. A method for producing a photoelectric conversion device, wherein the semiconductor layer is formed by applying and baking a liquid paste obtained by adding fine particles of an organic resin as a dispersed phase to the liquid paste.   A dye-sensitized photoelectric conversion in which a porous oxide semiconductor layer made of a sintered body of oxide semiconductor fine particles and an electrolyte layer are formed by laminating a plurality of layers and supporting a dye on a conductive substrate. In the device manufacturing method, the average particle diameter of the primary particles before sintering of the oxide semiconductor fine particles constituting each layer of the porous oxide semiconductor layer formed by laminating a plurality of layers is the same, and A porous oxide semiconductor layer is formed by applying and baking a colloidal liquid paste in which a dispersed phase is a primary particle of the oxide semiconductor fine particles and a dispersion medium is a liquid, and the porous oxide on the light emitting side is formed. A method for producing a photoelectric conversion device, characterized in that the semiconductor layer is formed by spraying and baking an aerosol in which fine particles of an organic resin are added as a dispersed phase to the liquid paste and a gas is added as a dispersion medium. . A photovoltaic device comprising the photoelectric conversion device according to claim 1 or 2 as a power generation means, and the power generated by the power generation means is supplied to a load.

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